Abner Ramirez and Amanda Sudano look like very happy people. Not the annoying kind. The I-want-to-be-like-them kind.

The first time Ramirez saw Sudano, he said, “That’s the girl I’m going to marry,” and he did. Some couples complete each others’ thoughts. Ramirez and Sudano add to each other’s thoughts. Plus, they’re both really good looking, but that’s not their fault.

The public benefit of all this is that Ramirez and Sudano share not just a romantic harmony. but also a musical one. They are Johnnyswim, a Los Angeles-based duo that’s quickly winning devotees with pop songs that draw on rock, soul and Nashville influences. The chemistry the two project on record and stage is undeniable.

Johnnyswim is scheduled to perform at the Fox Theatre in Boulder on Sunday night. Local singer-songwriter Jeff Brinkman, a former contestant on the reality-TV show “X Factor” in 2013, opens the concert.

Ramirez and Sudano met in Nashville, Tenn., and Ramirez says he used the whole music thing as a way to hang out with Sudano. Once they fell in love, Ramirez had a relatively easy introduction to Sudano’s family, he said. Her mother is the late singer Donna Summer, who also married a musical collaborator, Bruce Sudano, Amanda’s father.

“I had the easiest path of all three sons-in-law,” Ramirez said during a recent phone interview.

The newest member of the family is Joaquin, Sudano and Ramirez’s son, who was born in February. The birth has meant major changes in their lives — they haven’t been able to spend as much time on the road, for example — but the changes have been for the better, according to Ramirez.

“We always say the worst thing for a writer is to not live, to not have a life,” he said, adding, “Joaquin has been the biggest piece of our heart we never knew we have.”

Johnnyswim’s debut album, Diamonds, came out last year, and they quickly found themselves being compared to The Civil Wars, were invited to “The Late Show With David Letterman,” NPR’s “Tiny Desk Concerts” and other national showcases.

The duo plans to release a live album in September, and dive into the studio for a second album in the fall.

“It’s an action-packed year for us,” Ramirez said.

The two are known to get serious about food, even when they’re on the road. They plan cuisine into their tours. When they arrive at a new place, Sudano checks the local dining options before anything else.

“One of the first things as we roll in, I’m on Yelp,” she said.

She has a party trick — name any city or venue Johnnyswim has played and she’ll tell you what they had for dinner that night. So a reporter asked her what she had last time Johnnyswim was in Boulder, and she admits they have yet to properly explore the offerings.

“We had hot dogs, pizza and candy,” she said.

They plan to do more rigorous culinary research in Boulder this weekend, they said. Got that, local restaurants?